Investigating the efficacy of supplementation with a proprietary dairy powder in supporting muscle recovery following exercise-induced muscle damage in healthy individuals

INTERVENTION: This is a double‐blind, placebo controlled, parallel design intervention study that will allow us to evaluate whether long‐term supplementation with dairy powder supplement promotes muscle recovery following eccentric exercise‐induced muscle damage to the quadriceps. Prospective participants who have passed the study's inclusion/exclusion criteria will be asked to attend a familiarisation session (approximately 1 hr) where they will meet with the study’s principal investigator. During this session, the study’s trial coordinator (Research Associate, approx. 5 years experience in human studies) and principal investigator (Research Scientist, PhD) who will introduced them to the subjective visual analogue scale (VAS) and questionnaire for pain assessment that they will be asked to respond to during the trial days. Each participant’s quadriceps muscle function will be measured using a Biode Xisokinetic dynamometer where they will be asked to perform three maximal concentric, eccentric and isometric contractions. Muscle function measures on quadriceps of both legs will be conducted. Participants will be also be familiarised to the bench stepping exercise that they will need to complete during the trial day. Participants will be required to step up (concentric) on a bench set at a height of 110% of their lower leg length then by step down (eccentric) from the bench with the contralateral leg at a speed of 15 cycles per minute for two minutes. During this exercise, participants will wear a weighted vest containing an additional mass corresponding to 15% of their bodyweight. Recruited participants will be evenly randomised into two treatment groups: (1) Dairy powder is a spray‐dried buttermilk powder with a comple Xblend of lipids comprised of saturated (13%) and unsatu CONDITION: Muscle damage; ; Muscle damage Musculoskeletal ‐ Normal musculoskeletal and cartilage development and function PRIMARY OUTCOME: Composite measures of muscle function parameters will include absolute and average peak torque from five maximal isometric, eccentric and concentric quadriceps contractions[These assessments will be conducted before and immediately after the bench‐stepping exercise on exercise trial days. Muscle function will also be measured 24, 48, 72 and 96 hours post exercise trial days.] Subjective measures of muscle soreness[Participants will be asked to complete a short‐from McGill pain questionnaire and give a soreness score before and immediately after the bench‐stepping exercise on exercise trial days. These same assessments for pain will also be measured 24, 48, 72 and 96 hours post exercise prior to muscle function assessments.] INCLUSION CRITERIA: Healthy males and females who are not involved in any comprehensive exercise training regime and can complete the physical requirements of the exercises (determined from the familiarisation day) will be selected for this study. Participants will be required to complete a health questionnaire and provide written consent for this study. SECONDARY OUTCOME: Composite biomarkers of inflammation ‐ plasma concentrations of IL‐4, IL‐2, CXCL10 (IP‐10), IL‐1ß, TNF‐a, CCL2 (MCP‐1), IL‐17A, IL‐6, IL‐10, IFN‐gamma, IL‐12p70, CXCL8 (IL‐8), TGF‐ß1 and RANTES[These biomarkers of muscle damage will be measured from blood samples collected before and immediately after the bench‐stepping exercise on exercise trial days and at timepoints corresponding to 24, 48, 72 and 96 hours post exercise. These parameter will be assayed using a bead‐based multiple Xpanel and measured by flow cytometry. RANTES will be quantified using a commercially available kit.] Composite biomarkers of tissue damage (creatine kinase activity, myoglobin, plasma cartilage oligomeric matri Xprotein (COMP) and CTX‐II concentrations) will be measured from plasma samples.[These biomarkers of muscle damage and cartilage degradation will be measured from blood samples collected before and immediately after the bench‐stepping exercise on exercise trial days and at timepoints corresponding to 24, 48, 72 and 96 hours post exercise. Creatine kinase activity will be measured by a commercial medical testing laboratory. COMP and CTX‐II will be measured using a commercial assay kits.] Composite cell phenotyping of circulating blood leukocytes[White blood cells isolated from venous blood before and immediately exercised will be stained with fluorophore‐conjugated antibodies and analysed by flow cytometry for white blood cell phenotyping (granulocytes, monocytes and lymphocytes). White blood cells from venous bloods collected at 24, 48, 72 and 96 hours post exercise will also undergo the same analysis.]